1. Field of the Invention
The present invention relates to a resource assigning method for assigning various resources to predetermined tasks for processing, and more particularly to an improvement of assigning method preferable for a communication resource assigning method for assigning communication resources such as prepared frequency bands to a plurality of communication information for transmission. The present invention relates to a base station and a terminal unit to which this communication resource assigning method is applicable.
2. Description of the Related Art
Mobile communication using a radio telephone system involves multiple accesses in which a plurality of mobile stations (terminal units) are connected to a single base station. In the case of radio telephones, a single base station is used by a large number of terminal units, so various communication methods have been proposed that serve to avoid interference among terminal units. Conventional communication methods of this kind include, for example, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA).
For example, in the TDMA method, one transmission band (a frequency channel) is separated using a predetermined time unit in order to form time slots, and a predetermined number of time slot periods form one TDMA frame. Each time slot in one TDMA frame is assigned to each terminal unit so that a plurality of terminal units can be connected to a base station using one transmission band.
In communication methods other than the TDMA method, basically, slots replacing the time slots used in the TDMA method are formed in a predetermined manner to enable multiple accesses.
Whatever communication method is applied, the capacity that can be transmitted during one time (for example, one time slot in the TDMA method) is fixed and the transmission capacity between a base station and a terminal unit is constant. Radio telephone systems generally set the amount of speech data that can be transmitted.
Recent radio telephone systems, however, may transmit various data (for example, facsimile image data, electronic mail data, and Internet data) other than speech data as transmit data, and a constant transmission capacity suitable for speech data is often insufficient for these data.
In a radio telephone system using such data, the transmission capacity is preferably variable, but if a plurality of data having different transmission capacities are mixed together as transmit data manipulated by each base station, the control of transmission will be complicated. That is, to appropriately determine how to assign a communication resource such as a frequency band to each base station in order to set the capacity of communication with each terminal unit, the number of terminal units simultaneously connected and the communication capacity of each terminal unit must be determined in assigning channels. Then, complicated control is required to assign appropriate channels in real time depending on the number of terminals and the communication capacity that constantly vary.
In particular, to execute frequency hopping in which the frequency used between a terminal unit and a base station is sequentially switched so that prepared frequency bands can be evenly used, channels must be assigned in such a way that if a plurality of communication lines of different capacities are mixed together, they can be frequency-switched appropriately. Thus, much complicated control is required.
The problem has been described which may occurs when a radio telephone system requires lines of different transmission capacities to be mixed together for communication. However, if, for example, a data processing unit such as a computer unit requires data (tasks) of different capacities to be mixed together for data processing and the data of the respective capacities are assigned to certain items (resources) for processing, the assigning processing will be complicated.